@inproceedings{niemela97lpmnr,
  author    = {Ilkka Niemel{\"a} and
               Patrik Simons},
  title     = {Smodels - An Implementation of the Stable Model and
Well-Founded
               Semantics for Normal LP},
  booktitle = {LPNMR},
  year      = {1997},
  pages     = {421-430},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}